Child proof caps for medicine vials and the like are well known. Such caps however do not provide an air tight seal which is often required to prevent spoilage of the contents of such vials. Plug fitments are used as air tight seals. Characteristically such fitments are plastic hollow somewhat flexible cylinders with an end that tapers inward, the tapered end being inserted removably into the neck or other suitable opening.
There is a clear need for child proof plug fitments which cannot be removed from the vial by a child. The only plug fitment known to applicant which is supposedly child proof has been described above in the prior art statement. This known fitment however has been found to be unsatisfactory in that some children have learned by trial and error how to remove the fitment whereby it is not completely child proof.
The present invention overcomes this difficulty and provides a plug fitment which is not only child proof but which cannot be removed from a vial without damage by an adult who does not know how to remove the fitment.